The present invention relates to ink-jet printers, and, more particularly, to alignment of the printhead and carriage and an electrical interconnect lock-in mechanism for controlling the printhead.
In ink-jet printing technology, a printhead, comprising a plurality of nozzles in a nozzle plate, is fluidically associated with a reservoir of ink. The printhead is mounted on one end of a print cartridge and the reservoir is provided inside the cartridge. Reference is made to U.S. Pat. No. 4,755,836, issued to Ta et al. on Jul. 5, 1988, and assigned to Hewlett-Packard Company.
An interconnect means is provided, which carries electrical signals from a microprocessor in the printer to the printhead. For thermal ink-jet printers, these signals provide a current to resistors associated with the nozzles and thus control the heating of specific resistors, which in turn form droplets of ink. The droplets of ink are expelled through the nozzles toward a print medium, such as paper. The particular pattern of resistor heating controls the pattern of characters formed on the print medium.
The print cartridge is supported in a carriage, which is adapted to move bidirectionally, normal to the movement of the print medium through the printer. The carriage movement is controlled by a motor and an associated belt drive, with the motor controlled by the microprocessor.
Insertion of an ink-jet cartridge into the carriage often necessitates use of two hands or two operations. Further, many cartridge/carriage configurations do not provide simultaneous alignment of the nozzle plate in the X, Y, and Z directions. Finally, contact between the printhead and the interconnect means must be reliably made, in order to ensure proper nozzle firing.
Accordingly, it is desired to provide a cartridge/carriage assembly that includes the foregoing advantages without the limitations of the prior art.
In accordance with the invention, a printhead cartridge and carriage assembly is provided comprising:
(a) a carriage;
(b) means for securing a printing cartridge in position in the carriage; and
(c) interconnect means for supplying electrical signals to the cartridge, including force loading means for urging the interconnect means against the cartridge.
The cartridge has top, bottom, sides, front and rear surfaces and includes a printhead on the bottom surface, a contact on the back surface connected to the printhead, referencing pads on the side surfaces, and a lip on the back surface for accepting a snap spring for locking the cartridge in position in the carriage. The securing means includes the snap spring and means for receiving the referencing pads on the cartridge. The force loading means urge the interconnect means against the contact of the cartridge.
The printhead cartridge/carriage assembly of the invention requires only one hand of the operator to both insert and lock the cartridge in position. Further, the cartridge/carriage assembly provides simultaneous alignment of the nozzle plate in the X, Y, and Z directions. Finally, contact between the printhead and the interconnect means is reliably made each time the cartridge is inserted and locked in position, thereby ensuring proper nozzle firing each time.